Wet Limestone FGD-Controls

Wet Limestone

FGD-Controls

Module 6

Welcome Screen

Wet Limestone FGD-Controls Course Overview

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Flue-gas Desulfurization (FGD)

01 02 03 04 05 06

Basics of

SO2&

Regulation

Desulfurisation

Technologies FGD

Process

Major

Process

Equipment

Balance of

Plant

Equipment

FGD –

Controls

Wet Limestone FGD-Controls

Hi there, I’m Mr. Tech. I

am here to explain all

about Wet limestone

FGD –Controls

to you.

Module Overview and Objectives

This slide can be removed if overview is

FGD controls

1Typical DCS

configuration

2Major control loops -

Absorber

pH / Reagent feed

control

4pH instrumentation

5Gypsum bleed/ solid

controls

Gypsum solids /

density control

7Density

measurement

8Level / make up water

control

Booster fan control

10 Emergency quench

11 Summary

Assessment

Wet Limestone FGD-Controls Topic Introduction

Module Outline

Click on the first icon to start the module.

FGD Controls

Typical System

Configuration

Major Control Loops

Assessment

Wet Limestone FGD-Controls

FGD Controls

Let’s begin by

understanding

what FGD

Controls is.

Topic Introduction

Wet Limestone FGD-Controls Control System and Option Types

Select each box to know the details.

Augmentation of existing Main Plant

Distributed Control System (DCS)

Standalone Programmable Logic Control

(PLC) system

Major and Special Instruments

Continuous Emission Monitoring System

(CEMS)

Let us start with

control system and

options type.

Wet Limestone FGD-Controls

Select each box to know the details.

Augmentation of existing Main Plant

Distributed Control System (DCS)

Standalone Programmable Logic Control

(PLC) system

Major & special instruments

Continuous Emission Monitoring System

(CEMS)

Control System and Option Types

•Control and operation of main plant is

carried out through Distributed control

system or DCS

•Extending/augmenting this DCS system

is preferred for seamless FGD control,

monitoring & operation from Main Plant

Control room.

Augmentation of existing Main Plant

Distributed Control System (DCS)

Wet Limestone FGD-Controls

Select each box to know the details.

Augmentation of existing Main Plant

Distributed Control System (DCS)

Standalone Programmable Logic Control

(PLC) system

Major & special instruments

Continuous Emission Monitoring System

(CEMS)

Control System and Option Types

•PLC control systems are widely considered

for sub systems and relatively smaller

requirements.

•If PLC system, it shall be integrated with

Exiting DCS system for remote operation

and monitoring from Main Plant Control

room.

Standalone Programmable Logic Control

(PLC) system

Wet Limestone FGD-Controls

Augmentation of existing Main Plant

Distributed Control System (DCS)

Standalone Programmable Logic Control

(PLC) system

Major & special instruments

Continuous Emission Monitoring System

(CEMS)

Select each box to know the details.

Control System and Option Types

•pH analyzer, Density meter, FGD inlet SO2 &

O2 analyzer, lime stone slurry flow

measurement are critical process

parameters.

Major instruments & special

instruments

Wet Limestone FGD-Controls

Select each box to know the details.

Augmentation of existing Main Plant

Distributed Control System (DCS)

Standalone Programmable Logic Control

(PLC) system

Major & special instruments

Continuous Emission Monitoring System

(CEMS)

Control System and Option Types

CEMS is very critical system and it comprises of

multiple analyzers for various parameter SO2,

NO, NO2, CO, CO2, O2, moisture, pressure, flow,

temperature of flue gas monitoring in

compliance to MoEF (Ministry of Environment, Forest and

Climate Change) and pollution board requirements.

It is used for real time air emission monitoring

by Pollution control boards.

Continuous emission monitoring system

(CEMS)

Wet Limestone FGD-Controls Controls, Safety and Redundancy in System

Critical equipment and

process control is

enhanced with triple

redundant parameter

monitoring for all trip

events. All control

measurements are Dual

redundant.

Complete plant

operation and control

parameters (the

parameters used for

automatic control and

operation)is ensured

through redundant

instrument for better

reliability & safety of

FGD plant.

High-tension drives

(powered at 0.6 kV or

higher) are equipped

with a vibration

monitoring system to

ensure man, machine

and process safety.

The complete FGD

plant is designed with

surveillance for both

operational and non-

operational areas and

access control checks

to regulate the plant's

unauthorized entry and

unauthorized

operation.

Wet Limestone FGD-Controls Topic Introduction

Module Outline

Click on the first icon to start the module.

FGD Controls

Typical System

Configuration

Major Control Loops

Assessment

Wet Limestone FGD-Controls

Typical System Configuration

Now, let’s move to the

next to Typical

System

Configuration.

Topic Introduction

Wet Limestone FGD-Controls Typical System Configuration

Select the different levels to know more.

This is the basic

architecture of FGD

control system.

Wet Limestone FGD-Controls Typical System Configuration

Level 0 (Heart of the

control system),

comprising field

instruments,

transducers, sensors

and transmitters. The

major monitoring in the

FGD plant is pH,

Density, SO2,

analysers, flow,

pressure, temperature,

and level transmitters

as major process

parameters.

Select the zoom icon to know more.

Wet Limestone FGD-Controls Typical System Configuration

Level 1 or the

Input/output modules -

This is the part of the

control system that

connects the field

instrument to the

controller/processor of

the control system.

Along with these

modules, marshalling

or termination cabinets

play a major role in the

cabling of the FGD

system.

Select the zoom icon to know more.

Wet Limestone FGD-Controls Typical System Configuration

Level 2

Controller/processor of

the control system is

the control system's

brain. Entire

computing, analysis

and logic are

programmed into this

processor/controller,

which automates the

entire FGD plant.

Essentially, the logic in

controllers is to

interpret the

information relayed by

the transmitter/field

instrument to monitor &

act on the required

plant/equipment/proces

s operation.

Select the zoom icon to know more.

Wet Limestone FGD-Controls Typical System Configuration

Level 3 This layer is

also known as the user

interface level, where

HMI (Human machine

interface) is used for

the operation and

monitoring of the plant

by an operator.

Select the zoom icon to know more.

Wet Limestone FGD-Controls

Which of the following level is known as user interface level?

Select the correct option and click Submit.

•Level 0

•Level 1

•Level 2

•Level 3

SUBMIT

Knowledge Check

Wet Limestone FGD-Controls Topic Introduction

Module Outline

Click on the first icon to start the module.

FGD Controls

Typical System

Configuration

Major Control Loops

Assessment

Wet Limestone FGD-Controls Topic Introduction

Major Control Loops

Let’s understand the

Major Control Loops.

Wet Limestone FGD-Controls Major Control Loops List

Now, let us start with

the different kinds of

Major Control Loops.

Bypass Damper control for close

condition

Open Loop Controls

Absorber control loops

Close Loop Controls

Make up water

FGD Trip signals

analyzer

Coriolis type Density meter

Booster Fan

start Control

Booster Fan control

loops

Wet Limestone FGD-Controls Open and Closed Control Loops List

Open Loop Controls Closed Loop Controls

Select each tab to know more.

Wet Limestone FGD-Controls

FGD Start Sequence control

FGD safe shutdown sequence controls

RC Pump sequence start stop controls

Gypsum bleed pump operation Sequence control

Open and Closed Control Loops List

Open Loop Controls Closed Loop Controls

Wet Limestone FGD-Controls

FGD Bypass Damper control

BUF blade pitch control

Absorber Level control

PH and density control in wet lime-stone

Open and Closed Control Loops List

Open Loop Controls Closed Loop Controls

Wet Limestone FGD-Controls

Trip = Unplanned, uncontrolled, ”emergency” shutdown of a machine or process or piece of

equipment.

Example:

High vibration of a piece of rotating equipment, it’s known to “trip” that equipment.

FGD Trip signals

Coming to FGD

Signals.

Equipment/proces

s criticality

Equipment OEM

recommendation

Process Safety

The Trip conditions are based on:

Wet Limestone FGD-Controls FGD Trip signals

Failure of all RC

Pumps

Trip

Conditions

for the FGD

plant

Power Black out

Flue Gas Inlet

temperature Hi

Bypass Damper

Open

Both Booster fan

Trip

Absorber Level

Very High

Wet Limestone FGD-Controls Major Control Loops List

Coming to knowing

about Fail Safe

Condition.

FGD plant starts

Sub-system is lined

FGD scrubber tower

or absorber is ready

for flue gas entry

Wet Limestone FGD-Controls Bypass Damper control for close condition

At this stage, the flue gas is directed to the absorber through sequential operation, ensuring

permissive conditions for safe operation for equipment to enable the FGD start. Fail safe Conditions

include:

Booster Fan Inlet / Outlet Guillotine damper open

Two RC pump in operation

Flue Gas Inlet temperature Normal

Flue Gas Inlet pressure not low and High

Accumulator Pressure is normal

Wet Limestone FGD-Controls Booster Fans

Select each tab to know more.

Booster Fan Start Control Booster Fan Control Loops

Let us now learn

about Booster

Fans.

Wet Limestone FGD-Controls

Major Control Loops start the Booster Fans, both the inlet and outlet dampers should be opened and the blade pitch actuator is set

to minimum position.

Any One ID Fan of respective boiler is

running.

Guillotine damper at Inlet/Outlet shall be

closed.

Two absorber recycle pumps are working.

Emergency water storage tank liquid level

above HIGH.

Mist eliminator wash water pump running.

Mist Eliminator water wash cycle in auto-

cycle in Auto.

Bypass Damper is open and Open

feedback available.

Booster Fans

Booster Fan Start Control Booster Fan Control Loops

Wet Limestone FGD-Controls

Axial type booster fan with variable blade pitch actuator converts the positioning signal to a mechanical movement. It

can be interlocked with unit load.

Booster Fans

Booster Fan Start Control Booster Fan Control Loops

Wet Limestone FGD-Controls

Limestone

slurry feed

Make up

water

Gypsum

bleed

Limestone slurry feed

is the limestone slurry

added based on pH

of the absorber slurry.

Makeup water is

based on

absorber level.

Gypsum

bleed is

based on

absorber

slurry

density.

Absorber Control Loops

Coming to Absorber

Control Loops, the

diagram shows control

loops for different inputs.

Wet Limestone FGD-Controls

pH sensor

Piping

pH Transmitter

Field display

pH analyzers are used for measuring pH of

absorber slurry. As well as, controls the limestone

slurry addition in the absorber depending on the

pH values.

Next on list are the pH

Analyzers.

pH Analyzers

Wet Limestone FGD-Controls

•Limestone slurry makeup is

added based on absorber

slurry pH.

•Outlet SO2can also be used

for controlling limestone slurry

addition.

•A pH of 5 to 6 is maintained

inside the absorber.

pH Control loop

pH monitoring is the

next control loop to

cover.

Wet Limestone FGD-Controls

ABSORBER

HIGH-HIGH

HIGH

MEDIUM

LOW

LIMESTONE

SLURRY FEED

VALVE

LOW-LOW

FILTRATE

VALVE

ABOVE

BELOW

STOP STOP

STOP

START

MAKEUP WATER

VALVE

MIST ELEMINATOR

WASH SEQUENCE

START

Note to SME: No audio has

We will be needing inputs

Absorber Level Control

Wet Limestone FGD-Controls

yes from 0.06 to 2.50

•Works on the principles of motion mechanics

•Splits when the process fluid enters the sensor

•Leads the drive coil to stimulate the tubes to oscillate in

opposition at the natural resonant frequency on operation. As

the tubes oscillate, the voltage generated from each pickoff

creates a sine wave.

Coriolis type Density meter

The Coriolis type

Density meter is next

control loop.

Wet Limestone FGD-Controls

The Density control is based on

the slurry density at the gypsum

bleed pump discharge.

Gypsum slurry will be

discharged into the primary

hydro cyclone feed tank or

recirculated back to the

absorber.

The density range is 1.2-1.3

T/m3 to discharge into the

primary hydro cyclone tank.

Density Control loop

Wet Limestone FGD-Controls Emergency quenching water system

An emergency quench system consists of

an Emergency water tank, auto valve and

spray nozzles.

Quench water from the Emergency water

tank is sprayed into the quenching zone of

the flue gas duct before the absorber takes

it by gravity.

The system is designed to supply

emergency water for 15 minutes and get

activated on the high temperature of inlet

flue gas.

Wet Limestone FGD-Controls

When do the major control loops start the booster fans?

Select the correct option and click Submit.

•When both the inlet and outlet dampers are opened and the blade

pitch actuator is set to minimum position.

•When the outlet dampers is open and the blade pitch actuator is set to

minimum position.

•When the inlet dampers is open and the blade pitch actuator is set to

maximum position.

•When both the inlet and outlet dampers are opened and the blade pitch

actuator is set to maximum position.

SUBMIT

Knowledge Check

Wet Limestone FGD-Controls

Which one of the following is based on slurry density?

Select the correct option and click Submit.

•Makeup Water

•Limestone Slurry

•Gypsum Bleed

•A and B both

SUBMIT

Knowledge Check

Wet Limestone FGD-Controls

Which of the following does the Emergency quench water

system gets activated on?

Select the correct option and click Submit.

•High temperature of flue gas

•Tripping of all RC pumps

•Low temperature of flue gas

•A and B both

SUBMIT

Knowledge Check

Wet Limestone FGD-Controls Topic Introduction

Module Outline

Click on the first icon to start the module.

FGD Controls

Typical System

Configuration

Major Control Loops

Assessment

Wet Limestone FGD-Controls

Assessment

It is time to take

the assessment

now

Assessment

Wet Limestone FGD-Controls Assessment

You have completed the module on Wet Limestone FGD course - Controls and you are ready to take the

module assessment. Please note:

You must complete all questions in one session. If you exit the assessment before all questions are answered,

your answers will not be saved

You need a minimum score of 75% to pass the assessment

You can retry the assessment if you do not achieve the minimum passing score

Good Luck !

BEGIN

Assessment

Test Yourself

Wet Limestone FGD-Controls

SUBMIT

Question 1 of 5

With which of these does the Emergency quench water system get

activated?

Assessment

High temperature of flue gas

Tripping of all RC pumps

Low temperature of flue gas

A and B both

Select the correct option and click Submit.

Wet Limestone FGD-Controls

SUBMIT

Question 2 of 5

Primary hydrocyclone feed is opened at which of the following density

range?

1.8-2.3 T/m3

0.2-0.3 T/m3

1.2-1.3 T/m3

1.6-2.1 T/m3

Select the correct option and click Submit.

Assessment

Wet Limestone FGD-Controls

SUBMIT

Question 3 of 5

Which level is known as the control system's brain?

Level 2

Level 3

Level 0

Level 1

Select the correct option and click Submit.

Assessment

Wet Limestone FGD-Controls

SUBMIT

Question 4 of 5

ME wash system is activated on H-H level of absorber slurry.

•True

•False

Select the correct option and click Submit.

Assessment

Wet Limestone FGD-Controls

SUBMIT

Question 5 of 5

pH is very crucial parameter for deciding the absorber efficiency.

•True

•False

Select the correct option and click Submit.

Assessment

Wet Limestone FGD-Controls Assessment

Result

Your score: [ ]%

You have successfully completed the module on Wet

limestone based FGD –Control Process.

Click the Exit button to exit the course.

Congratulations!

EXIT

Assessment

Wet Limestone FGD-Controls Assessment

Result

Your score: [ ]%

You need to score 75% or more to pass this assessment.

To retake the assessment, click Retake.

Click the Exit button to exit the course.

Sorry!

RETAKE

Assessment

Wet Limestone FGD-Controls

Thankyou!